JP2000-81071A and JP2010-175043A disclose a shock absorber having an outer shell and a piston rod inserted into the outer shell to be free to advance and retreat. The shock absorber is configured such that when the piston rod moves in an axial direction relative to the outer shell, a damping force is generated to suppress the relative movement between the piston rod and the outer shell. The shock absorber is disposed in a vehicle between a vehicle body and an axle or between a cabin and the vehicle body, for example, in order to suppress vibration of a damping subject such as the vehicle body or the cabin using the damping force.
The shock absorber is exposed to the outside during use, and therefore dust, dirt, and so on are likely to adhere to the piston rod of the shock absorber. When the piston rod advances into the outer shell, the dirt and so on adhered to an outer periphery of the piston rod are scraped away by a dust seal that seals the outer periphery of the piston rod. When dirt and so on dry out so as to adhere firmly to the piston rod, the dirt and so on adhered to the piston rod cannot be scraped away by the dust seal, and may cause an oil seal provided inside the dust seal to deteriorate. Therefore, the shock absorber is provided with a dust cover that covers the outer periphery of the piston rod so that the piston rod is protected from dirt and so on by the dust cover.